API Energy Drain Back System, which is a type of active system, use pump station to circulate water through the collectors. The water in the collector loop drains into a reservoir tank when the pumps stop by controller. This makes Drain Back system a good choice in colder climates. Drain Back system must be carefully installed to assure that the piping always slopes downward, so that the water will completely drain from the piping. This can be difficult to achieve in some circumstances.

API Energy thermal solutions offers more competitive efficient Drain Back Solar System, which uses API Energy Heat Exchanger in the API Energy Drain Back tank and hence reduce the energy lose in the vented drain back tank and also one circulation pump is required in the Solar Heating Side.